Two main areas, each comprising three fields — forming a coherent inquiry into the normative foundations of law, its theory of rights, and its institutional structure across competing authorities and jurisdictions.
My central theoretical contribution is a triadic concept of law — comprising its real, ideal, and discursive dimensions — which extends and reconstructs Alexy's dual-nature thesis by adding the discursive dimension as a constitutive element of legal normativity. On this basis, I defend a non-positivist position: law's claim to correctness is not an external moral standard imposed upon law, but internal to the concept of law itself.
My work develops integrative jurisprudence — the thesis that legal scholarship is primarily analytico-normative in character, yet must coherently incorporate empirical methods. This position flows from the triadic structure of law itself and shapes my account of the disciplinary relationships among the various legal sub-disciplines on the one hand, and between law and related disciplines such as philosophy, social science, and political theory on the other.
My work centres on the normativity and rationality of legal argumentation — showing that the binding force of legal language is neither purely logical nor a matter of judicial discretion, but structurally analysable and rationally reconstructable. I pursue this through research on the triadic nature of legal argumentation, and more specific issues like constitutionally conforming interpretation and the role of precedent in legal reasoning.
I defend the extension of constitutionalist frameworks beyond the state against sceptical critics, arguing that constitutional principles are not intrinsically tied to the nation-state. My newest book, Authorities’ Concordant Order, develops a theory of the practical concordance of competences to resolve the jurisdictional conflicts that arise between national, European, and international legal orders.
My primary contribution is a systematic account of proportionality as a structurally determinate and rationally controllable practice — not arbitrary judicial weighing. I show how the five stages of proportionality analysis generate legally binding constraints on adjudication, and I apply this framework to positive rights, the balancing of competing rights, and the relationship between constitutional rights and other constitutional interests and values.
I pursue analytical research into the fundamental structures and principles of constitutional law across the national, supranational, and international levels — including democracy, the rule of law, judicial review, and the social welfare state. A recurring focus is how constitutional theory can account for competing legal authorities and multi-level governance without sacrificing normative rigour.